The present invention relates to a protective covering for fiberglass booms. More particularly, the present invention relates to a surface covering for fiberglass booms used on aerial lift trucks which protects the boom from abrasions caused by the boom coming into contact with tree branches and guy wires when the boom is in use.
The present invention relates to mobile aerial lifts of the so-called "cherrypicker" type which conventionally comprise a mobile platform or truck upon which an articulated boom structure is provided for three-dimensional operation. The lower end of the articulated boom structure is conventionally rotatably mounted on the truck body. The other end of the articulated boom structure is provided with a personnel carrying bucket which is usually maintained in a level position, regardless of the position and elevation of the boom.
Such aerial lifts are conventionally used in the construction or maintenance of electrical power lines, and it is quite common for workmen to work on energized high-voltage power lines from the personnel carrying bucket in an elevated position. For this purpose, it is essential in the first instance that the physical structure of the boom be maintained in a good condition so as to be sufficiently strong to support the weight of a workman as well as the equipment which it may be necessary for him to use while in an elevated position. However, due to the fact that workmen, such as linemen and electricians, are often called on to work on energized lines, it is necessary that the boom or a portion of an articulated boom be comprised of a dielectric material such as a fiberglass reinforced polymeric resin (referred to in a number of places herein as "fiberglass"). Even in cases where the aerial lift or cherry picker is used in industries other than the electric utility industry, it is often desirable to have at least a portion of the boom comprised of a dielectric material to provide a safety factor in the event that the boom or bucket accidentally comes in contact with an energized power line. For these reasons, it is important that the insulating or dielectric qualities of the boom be maintained.
The insulating qualities or dielectric strength of the boom may be adversely affected by the accumulation of various contaminating media on the surface of the fiberglass boom. Abrasions and cracks in the surface of a fiberglass boom tend to accumulate contaminating media such as dirt, dust, moisture and other foreign particles.
However, it is also essential that the condition of the fiberglass boom be capable of being visually examined for cracks or other deteriorations of the boom's condition. Therefore, it is important that any covering of the boom be transparent.